What three things happen when a ray of light crosses the boundary between one medium and another.

Copper has free electrons per cubic meter. a 71.0-cm length of 12-gauge copper wire that is 2.05 mm in diameter carries 4.85 a of current. (a) how much time does it take for an electron to travel the length of the wire? (b) repeat part (a) for 6-gauge copper wire (diameter 4.12 mm) of the same length that carries the same current. (c) generally speaking, how does changing the diameter of a wire that carries a given amount of current affect the drift velocity of the electrons in the wire?

To do work, this truck uses energy stored in chemical fuel and an electrical battery. how much total energy does this truck put out?

Which diagram correctly demonstrates the various forces acting on a ball moving horizontally with some speed?